Multi-pole electromagnetic relay with convertible contacts



Sept. 23, 1969 A. BROVEDAN 3,469,215

MULTLPOLE ELECTROMAGNETIC RELAY WITH CONVERTIBLE CONTACTS Filed May 23, 1967 3 Sheets-Sheet 1 w l! Il a il.. 4/ u 1 Sept 23, 1969 A. BRovEDAN 3,469,215

MULTI-POLE ELECTROMAGNETIC RELAY WITH CONVERTIBLE CONTACTS Filed May 23. 1967 3 Sheets-Sheet r,

l Sept? 23, 1969 A. BROVEDAN 3,469,215

MULTI-POLE ELECTROMAGNETIC RELAY WITH CONVERTIBLE CONTACTS Filed May 2:5. 1967 3 sheetsl-sheet s 3Q United States Patent O MULTI-POLE ELECTROMAGNETIC RELAY WITH 4CONVERTIBLE CONTACTS Antonio Brovedan, Milan, Italy, assignor to Pirelli Societa per Azioni, Milan, Italy, a corporation of Italy Filed May 23, 1967, Ser. No. 640,577 Claims priority, application Italy, May 24, 1966, 18,207/ 66 Int. Cl. H01h 67/02 U.S. Cl. 335-132 13 Claims ABSTRACT F THE DISCLOSURE An electrical relay with contacts which convert from a normally opened condition to a normally closed condition, and vice versa, by removing spring loaded contact units from one recess zone of a moveable contact carrier and reinserting the contact unit in another zone.

The present invention relates to multi-pole electromagnetic relays with convertible contacts, and more particularly it concerns a relay having movable electric contacts which may be manually engaged with and disengaged from, a contact carrier, and which may have their position changed from a normally opened condition to a normally closed condition.

Electromagnetic relays with convertible contacts have, in general, a large number of poles, and are constituted by a housing incorporating stationary contacts and connesting clamps. Located inside the housing is an electromagnet which controls a movable contact carrier.

When the relay of the present invention is in its rest or deenergized condition, it is possible to shift its electric contacts from a position in which they are normally opened to a position in which they are normally closed vand vice versa.

Depending upon the rest position of the contacts, in passing from the rest condition to the operating condition, it is possible either to open or to close an electric circuit.

Relays in which the position of the electric contacts can be converted from a normally opened condition to a normally closed and vice versa, are already known. In some such relays the position of both the stationary contacts and the movable contacts are changed. In this case, the movable contacts are disengaged from the carrier and then are re-engaged in a reversed position while the stationary contacts are on the other hand disassembled and re-assembled in a different position. It is therefore evident that, when the number of poles is large, the size of the relay is considerable and the conversion of the contacts becomes complicated.

Relays are also known in which only the position of the movable contacts is changed to obtain conversion.

In such case, however, these relays incorporate a suitable' structure which is assembled in the carrier and which, by means of a change of position, for instance a rotation about an axis, permits the contacts to become disposed in normally opened or in normally closed position. In these cases, the relay is composed of several pieces, the machining and the assembling of which is rather difiicult.

The present invention provides an improved multipole electromagnetic relay of the type in which the conversion of the contacts does not involve the above indicated drawbacks; and which conversion may be easily carried out manually without disconnecting the relay from the electric circuits associated therewith.

The present invention further provides an electromagnetic relay Which has convertible contacts, which is composed of a small number of component parts, which ice has a reduced size and which may be easily assembled and disassembled without the need of any special tool.

The present invention also provides a relay of the above indicated type, in which the compression of a relay return spring in rest position may be easily changed, so as to vary at will its reaction force, when this is desired.

The relay of the present invention comprises a housing and a carrier movable reciprocally between a first and a second position with respect to the housing. In the preferred embodiment window recesses are provided in the carrier and these window recesses are divided by means of lugs protruding thereinto from the carrier, into two zones displaced in the direction of carrier movement. A contact unit is positionable in either zone of each window recess. The contact unit comprises a first contact element and a spring secured thereto. The contact unit is placed in either zone of a window recess with the spring pressing against the outer recess wall and forcing the rst contact element against the lugs. A lfurther contact is carried by the housing and is positioned to be contacted by the irst contact element when it is in one window recess zone with the carrier in its first position and when it is in the other window recess zone with the carrier in its second position and to be otherwise displaced from the irst contact element. As a result the device may be shifted between normally closed and normally opened condition simply by manually shifting the zone of the contact unit.

In the preferred form of the invention, the carrier is spring biased to one of its positions and is electro. magnetically actuated to its other position. Also in the preferred embodiment the movable contacts are carried by a suitable unit constituted by a supporting bridge for the movable contacts, having a central slit, by an auxiliary T-shaped element, whose stem may slide in the slit of the bridge, and by a compression spring positioned about the stern of the T-shaped auxiliary element and acting between the latter and the bridge.

The movable contact unit can be manually engaged in, and disengaged from, the carrier, and its position therein can be changed to dispose the contacts selectively in a normally opened condition or in a normally closed condition, and vice versa.

The means for keeping the carrier in its deenergized or rest position includes a bar transversally disposed in the seat, which has its ends inserted in suitable seats of the housing. The bar is slidable in the direction of motion of the carrier and has associated therewith, a spring acting between the bar and the carrier.

The control electromagnet comprises a magnet circuit formed by a lixed portion and by a movable portion, or armature, both portions being preferably E-shaped. An energizing coil encircles their central leg.

In the illustrative embodiment of the invention, the housing of the relay is constituted by a base portion to which the fixed magnetic circuit is secured, and by two portions, containing the stationary contacts and removably assembled on the base portion with suitable connecting means so as to form a box-like outer housing.

The energizing coil and the fixed magnetic circuit can be independently connected to the base portion with separate fastening means, or a single fastening means can be used for both of them.

Relays having convertible contacts are normally multipole relays; therefore, it may be advantageous to dispose the stationary contacts along two parallel lines. In such cases, the poles are preferably four or eight in number, and the carrier is provided with as many windows for the movable contacts as there are poles, each obtained between the two facing stationary contacts of each pole.

In order to permit the contacts to be shifted between a normally opened and a normally closed position by changing the position of the movable contact unit, the windows of the contact carrier are made rectangular in shape and each of them, on both the inner faces of its longer sides, is provided with a projecting portion in a direction perpendicular to the motion of the carrier. The two projecting portions which face each other in each window divide the window into two zones, in either of which, as desired, the movable contact unit may be disposed. Depending upon the particular zone chosen, the contact may be shifted between normally opened and normally closed conditions. The windows are each provided with two protuberances along their inner faces at the sides opposite to each projecting portion.

The two protuberances in each of the window zones are received in suitable grooves obtained in the T-shaped auxiliary element; and these protuberances act as a stop for the movable contact unit disposed in the window. The T-shaped auxiliary element is also inserted in the slit of the supporting bridge and consequently its stem is shaped like a fork and the points of the fork are bent out so as to act as a stop for the bridge when this is inserted in the stem.

The housing of the relay is formed, as stated above, by a base part to which two further parts are removably assembled. For this purpose, in the illustrative embodiment of the invention, the base part is constituted by a flat bottom of rectangular shape surrounded by a frame which provides a lifted edge with respect to the at bot* torn. This frame, on two opposite sides, is provided with a lug for securing the base to an outer panel and, along its inside, it is provided with a suitable projection. A guide is provided on the other two sides of the frame, and this guide acts as a top for the two parts of the housing when these are in place on the base.

One wall of the two parts of the housing is provided with two appropriate tongues which enclose the inner projection of the sides of the frame; the two walls contiguous to it are provided with a suitable projecting ridge which engages with the means for connecting the two parts of the housing.

The means for connecting the two parts of the housing permits easy disconnection of these parts from the base and at the same time allows their disconnection also when the relay is installed.

For this purpose it is advantageous to include the connecting means on the base itself.

In a preferred embodiment of the invention the connecting means are constituted by a metal plate fastened to the base and by two braces slidable in guides formed on the sides of the frame. The braces are connected at one end to the metal plate. The braces are provided at their opposite end with two holes into which the projecting ridges of the two housing parts can be inserted.

An alternative embodiment of the invention provides a cross-shaped metal plate; in this case two arms serve, as in the preceding case, to the connection with the braces, whilst the other two arms are bent towards the inside of the base, the bottom of which is in that case provided with two suitable slots, and act as the only means for securing the xed magnetic circuit to the base. In the latter case it may be advantageous to cause the two U-folded arms of the metal plate to act as a means for securing to the base both the coil and the xed magnetic circuit at the same time.

Further details of the invention can be deduced from the following description, made with reference to the attached drawings, which represent by way of non-limiting example a particular embodiment of the invention.

In said drawings:

FIG. 1 is an overall perspective view of a four-pole electromagnetic relay forming one embodiment of the present invention;

FIG. 2 is an exploded perspective view of the relay of FIG. 1;

FIG. 3 is a top view of the relay of FIG. 1;

..4 FIG. 4 is a cross sectional view of the relay of FIG- URE l, taken along a plane passing through line 4-4 of FIG. 3;

FIG. 5 is a cross sectional view of the relay of FIG. 1, taken along a plane passing through line 5 5 of FIG. 3; FIG. 6 is an exploded perspective view of a movable contact unit forming one portion of the relay of FIG. 1;

FIG. 7a is a side elevational view of the movable contact unit of FIG. 6 in assembly, with the movable contacts being normally closed and the relay being in deenergized or rest position;

FIG. 7b is a view similar to FIG. 7a but showing the unit with the relay being in operating position;

FIG. 8a is a view similar to FIG. 7a, with the movable i contacts being normally opened;

FIG. 8b is a view similar to FIG. 8a but showing the unit with the relay being in operating position.

The relay shown in the various drawings incorporates four poles. As shown in FIGS. 1 and 2, there is provided a relay housing 1, formed by two parts 1a and 1b connected to a rectangular base 2 so as to form a box-like structure.

The housing 1 contains a control electromagnet and a contact carrier 6.

The control electromagnet is constituted by a magnetic circuit formed by a fixed magnetic part 3 and by a movable magnetic part or armature 4 and by an energizing coil 5. The two parts 3 and 4 of the magnetic circuit, which are of identical configuration, are formed by E- shaped laminations kept together for instance by riveting. Although it is not strictly necessary to buildup the magnetic circuit in two equal parts, in this way it is advantageously possible to use a single mould for the laminations thereby reducing the number of different parts which must be stocked for producing these relays. The parts 3 and 4 are both provided with grooves 7 and abutments 8 in their two lateral legs. These grooves and abutments serve to mount a shading coil 9 positioned in the fixed magnetic circuit. The length of the central leg of the armature 4 is reduced slightly from the outer legs so as to leave a gap, when the parts 3 and 4 are closed on each other. This facilitates the separation of the armature 4 from the fixed part 3 when the coil 5 is deenergized.

The two parts 1a and 1b of the housing 1 are identical and interchangeable. While this is not strictly necessary, it does serve to permit the use of a single mould for the two parts with a consequent reduction in the cost of forming and storing several different parts.

The two parts 1 and 2 are provided along their inside surfaces with a plurality of recesses 10. Stationary contacts 11 are encased within the recesses 10. A like num-v ber of outer recesses 12, corresponding to the inner recesses 10 are provided on the outside surfaces ofthe housing 1 and these outer recesses serve to encase connecting clamps 13.

A rectangular base 2 permits fastening of the relay to a panel or a supporting frame; and to this end it is provided, at its two outer opposite ends, with two securing lugs 14 which extend inwardly with projections 15. The latter are surrounded by two tongues 16 situated in the parts 1a and 1b to facilitate the closing of the housing.

Two ridges 17 on the other two sides of the base 2 are suitably shaped to act as a guide for two braces 18 and as a stop for the parts 1a and 1b. A spring 19, formed from a cross-shaped metal plate is secured to the base 2, for example by means of bushes; and two of its arms 20a are connected to the braces 18, whilst its other two arms 20h are U-shaped and penetrate inside the base 2 through suitable slots 20c formed therein.

The braces 18, having an elongated shape, are provided in their central portion with a longitudinal opening 21 and, at the ends opposite to the base, with two holes 22 which surround two projecting ridges 23 situated in the parts 1a and 1b.

The fixed part 3 of the magnetic circuit and the energizing coil 5, are connected to the base 2. As shown in FIG. 5, two rails 24, suitably disposed in the base 1, provide a seat for the fixed part 3. The coil 5 is inserted over the central leg of the part 3 and two cushion pads 25 and 26 (shown in FIGS. 4 and 5) are disposed between the base 1 and the fixed part 3 and between the xed part 3 and the coil 5. These cushions absorb any shocks which may be imposed on the fixed part 3 when the armature is actuated. The coil 5 moreover, has two lateral protrusions 27 which penetrate into suitable openings 28 formed in the arms 20b of the spring 19. In 4this way the coil 5 is pressed against the xed part 3 of the magnetic circuit and the fixed part 3 in turn is pressed against the base 2 of the relay, so that a very firm connection is obtained, which at the same time is very simple.

The coil 5 is provided with two terminals 29 which are inserted into suitable openings 30 formed in both parts 1a and 1b which, as stated above, are identical. A possible third opening 30a may be provided in these parts to allow observation of the coil 5 inside the housing.

The carrier 6, as can be seen in FIG. 4, is of rectangular shape; and within its periphery various partitions 31 are provided to dene window recesses 32. There are as many of these windows as there are poles of the relay. The carrier 6 is outwardly provided with two lateral ribs 33 which extend outside the housing 1 to ride in the longitudinal openings 21 of the braces 18, and a seat 34 (as shown in FIGS. 4 and 5) for the movable armature 4. The latter is directly moulded with the carrier so as to obtain a rm connection without any gap.

At the side opposite the armature 4, the carrier 6, is provided with a boss 35, with a threaded hole 36, which extends outside the housing 1 and may serve for the connection of the relay to other devices.

The central portion of the carrier 6, that is, the portion between the two partitions 31b, forms an aperture 37 for encasing a compression spring 38 which acts between the carrier 6 and a transversal bar 39 which slides in the aperture 37.

The window recesses 32, house movable contacts for the relay. These windows have a rectangular shape; and each of them carries on both inner faces of its longer sides, a projecting portion 41 which extends in a direction normal to the direction of motion of the carrier. There are also provided two protuberances 42 at the opposite sides of each projecting portion 41. The projecting portions 41 in each window divide the latter in two zones, namely an upper zone and a lower zone, in either of which movable contacts 40 may be inserted.

The movable contacts 40 form part of a contact unit, the details of which are shown in FIGS. 6, 7a, 7b, 8a and 8b.

This contact unit comprises a contact bridge 43 having a central slit 44, a T-shaped auxiliary element 45 and a compression spring 46.

The auxiliary element 45 has a fork-shaped stern 47, which terminates with two outwardly protruding points 48, and two lateral grooves 49. The .spring 46 is placed around the stem of the auxiliary element 45, and the stem then passes through the slit 44 of the bridge 43. The two parts of the fork-shaped stem 47 are bent together to permit the points 48 to pass through the slit 44. Thereafter the detachment of the bridge is prevented by the bent-out points 48 acting as a stop.

When the contact unit is disposed in the carrier 6 in normally opened position, that is when it is inserted in the upper zone of a window recess 32, the T-shaped auxiliary element 45 bears against an outer wall of the carrier 6 itself, while the bridge 43 is biased by the spring 46 against the projecting portion 41. The longitudinal protuberances 42, engaging in the grooves 49 of the T- shaped auxiliary element 45 prevent any transverse movement of the unit.

When the contact unit is assembled in the carrier 6, in a position such that the electric contacts are normally closed, the bridges 43 are not in contact with the projecting portions 41, but instead they rest on the stationary contacts 11. As can be seen in FIG. 7a the arms of the T-shaped auxiliary element 45 are encased in the recesses 10 of the parts 1a and 1b and are pressed against supporting planes 50 within these grooves. In this way the spring 46, closes the contacts, by producing a reaction which is directed against the housing itself.

The transversal bar 39 as shown in FIG. 5, protrudes into the housing parts 1a and 1b so that its ends 51 rest upon seats 53 in central zones 52 of the housing parts 1a and 1b. The central portion of the transversal bar 39 supports the lower end of the compression spring 38. The upper end of the spring presses upwardly on the carrier 6. In rest or deenergized condition, the spring 38 is slightly compressed so as to overcome the weight of the carrier 6 and to keep the boss 35 of the carrier out of the housing 1. When the carrier 6 lowers as a consequence of the energization of the electromagnet, the spring 38 becomes further compressed so as to provide, at subsequent deenergization, the return force necessary to bring the carrier back to its normal position.

As stated above, the boss 35 of the carrier 6 serves to permit connection of external devices associated to the relay. These devices generally exert a force on the boss 35, which tends to push the carrier down inside the housing toward its operating or energized position. This may tend to prematurely open the normally closed contacts and/ or close the normally opened contacts. To avoid this risk it is necessary to oppose the force exerted on the boss 35 by increasing the initial compression of the spring 38. To this end it is sufficient to raise (by means not forming a portion of the present invention), the ends 51 of the bar 39 at their point of support.

During operation of the device, the coil 5 is energized by supplying it with electrical current applied through the terminals 29. As a result of this energization the armature 4 of the electromagnet is attracted towards the fixed part 3 of the magnetic circuit. The carrier 6 which is integrally associated with the armature 4, moves with it; and is guided in such movement by the ribs 33 engaged in the openings 21 of the braces 18. In this way the normally opened electric contacts are closed and the normally closed electric contacts are opened.

When it is desired to change the operation of some contacts, i.e. to convert them from a normally opened position to a normally closed position, it is sufficient to detach the braces 18 from the projecting ridges 23 and to separate slightly the housing parts 1a and 1b, even while they are still connected to the wiring cables. This permits access to the carrier 6 for the carrying out of the conversion operation. This conversion is carried out by slightly pressing with two lingers, against the T-shaped auxiliary element 45 and moving it toward,the small bridge 43 so as to allow the disengagement of the movable contact unit from the carrier 6. Thereafter the contact unit is reengaged in the zone of the window recess 32 which is opposite to that in which the contact unit was formerly disposed. The contact unit is repositioned in an inverted arrangement so that the bridge 43 is still held by the side of the projecting portions 41. When the position of the contact unit has been changed as wished, the two housing parts 1a and 1b are again connected with the base 2 and with the braces 18.

The preceding description illustrates a particular embodiment of the present invention incorporating a fourpole relay. It will be readily apparent to those skilled in the art however, that the arrangement could easily be modified to provide an eight pole relay. In the case of an eight pole relay, the construction would differ from that illustrated in the figures only in that it would be provided with a second line of stationary contacts above the line existing in the four-pole relay. Of course, along with these additional stationary contacts, the two parts of the housing would be provided with grooves which would receive the stationary contacts; and these grooves would include a supporting plane for the T-shaped auxiliary elements in opened position. These latter would be disposed in the carrier, together with the contact bridges, in a second line of windows over that existing in the four-pole relay. All the other features remaining would be unchanged for both embodiments; and possible, but not necessarily, the number of turns of the energizing coil could be increased to obtain a greater attractive force for the armature 4 of the electromagnet.

Having t-hus described my invention with particular reference to the preferred form thereof, it will be obvious to those skilled in the art to which the invention pertains, after understanding my invention, that various changes and modifications may be made therein without departing from the spirit and scope of my invention, as defined by the claims appended thereto.

What is claimed as new and desired to be secured by Letters Patent is:

-1. An electromagnetic relay with convertible contacts, said relay comprising a housing which can be opened, an electromagnet, a carrier actuated by said electromagnet and movable between a rest position and an operating position within said housing, means resiliently biasing said carrier in its rest position said carrier being formed with a plurality of windows, and a plurality of movable relay contacts removably disposed in said windows, said movable contacts each being -a part of a separate removable contact unit, each contact unit including a contact carrying bridge provided with a central slit, a T-shaped auxiliary element having a stem slidable -in the slit of the bridge, -and a compression spring disposed about the stem of the auxiliary element and acting between the latter and said bridge, each contact unit being manually insertable in and removable from the carrier as a unit in each one of two positions within a corresponding window to convert the movable contacts from a normally open position to a normally closed position and vice-versa.

2. An electromagnetic relay as in claim 1, wherein said windows lare rectangular with their longer sides parallel to the direction of movement of the carrier and each provided on both inner faces of said longer sides with a projecting portion having a direction normal to the motion of the carrier and with two proturberances on opposite sides of each projecting portion, the two projecting portions of each window facing each other and delining two zones in the corresponding window, the movable contact unit being positionable in either zone of each window to obtain respectively a condition in which the movable contacts are normally open and a condition in which the movable contacts are normally closed.

3. An electromagnetic relay as in claim 2, in which the T-shaped auxiliary element of the contact unit has a forkshaped stem with outwardly protruding points which serve as a stop for the contact carrying bridge and has its head formed with two lateral grooves engageable with the protuberances in the windows of the carrier.

4. An electromagnetic relay as in claim 1, wherein said housing is constituted by a base with a flat bottom of rectangular shape surrounded by a peripheral frame which provides a raised edge with respect to the bottom,

the two greater sides of said fr-ame being provided with v an outward lug for fastening said fiat bottom to a support and with an inward projection, the two smaller sides of said frame being provided with a guide, two removable housing parts assembled on said flat bottom to form a box-like structure and being each provided on walls thereof corresponding to the greater side of said base, with two tongues which enclose the inward projection of said greater side and, yon each of the walls corresponding to the smaller sides of the base, with a projecting ridge, and

means engageable with said ridges for connecting the two removable housing parts with the base, said guides on the sides of the base acting as a stop for the two removable housing parts.

5. An electromagnetic relay as in claim 4, wherein said windows are rectangular with their longer sides parallel to the direction of movement of the carrier and each provided on both inner faces of said longer sides with a projecting portion having -a direction normal to the motion of the carrier and with two protuberances on opposite sides of each projecting portion, the two projecting portions of each window facing each other and defining two zones in the corresponding window, the movable contact unit being positionable in either zone of each window to obtain respectively a condition in which the movable contacts are normally open and a condition in which the movable contacts are normally closed.

6. An electromagnetic relay as in claim 5, in which the T-shaped auxiliary element of the contact unit has a fork-shaped stem with outwardly protruding points which serve yas a stop for the contact carrying bridge and has its head formed with two lateral grooves engageable with the protuberances in the windows of the carrier.

7. An electromagnetic relay as in claim 4, in which the means for connecting the two removable parts of the housing with the base is constituted by a metal plate secured to the base and by two braces sliding in said guides on the sides of the base, said braces being connected at one end with the plate and provided at the other end with two holes which engage the projecting ridges of the two removable parts of the housing.

8. An electromagnetic relay as in claim 7, in which said metal plate is cross-shaped Iand the fiat bottom is provided with facing slots, two arms of the metal plate being connected to said braces and the other two arms being folded upwardly and inserted -through said slots of the base to engage a fixed part of the electromagnet for connecting it to the base.

9. An electromagnetic relay as in claim 8, in which said electromagnet includes an energizing coil and both fixed and movable magnetic members, said upwardly folded arms of the metal plate engage said energizing coil ,and said fixed magnetic member is sandwiched between said coil and said base, whereby said plate secures both said coil and said fixed member.

10. An electromagnetic relay as in claim 1, wherein said means for biasing said carrier -in its rest position is constituted by a bar which extends transversely across the interior of said housing and which is slidable with respect to said carrier in the direction of .carrier movement, and a spring .acting between said bar and the carrier.

11. An electromagnetic relay as in claim 4, wherein the electromagnet includes a fixed magnetic part and a movable magnetic part, both of which are E-shaped, and an energizing coil surrounding their common centr-al leg.

12. An electromagnetic relay as in claim 11, in which both the energizing coil land the fixed magnetic part are connected to the base with a single fastening means.

13. An electromagnetic relay as in claim 11, wherein said carrier is integrally connected to said movable magnetic part and is provided with a plurality of windows corresponding to the number of relay poles.

References Cited UNITED STATES PATENTS 2,924,685 2/ 1960 Burch 335-132 3,215,800 11/1965 Hurter 335-132 3,334,319 i 8/1967 Herrmann 335-132 BERNARD A. GILHEANY, Primary Examiner H. BROOME, Assistant Examiner 

